A New York architecture firm has proposed the construction of new islands for what purpose?

Answer: composting

A chain of 10 islands would contain composting facilities where garbage trucks would deliver waste to be processed.

Each borough would have at least one dedicated island each, and after waste processing, compost would be carried away by barge or train. The firm that developed the idea, Present Architecture, admitted it's a radical idea, but it does fit in with the city's Vision 2020: Comprehensive Waterfront Plan.